Process for hydrolyzing organic halides



aliases 2,13%6fi PMCESS EQE Manama @MANEQ dim W. Meyer, Nutley, N. 3.,smith Qormrahon. Efilwanhee,

ill; 5 i

s er to A. Win, a corporahon or New York No Erawing. nppiieationNovember 1?, 1937, Qerial No. 175.1%

The invention relates to a processior hydrolyzing organic halides andhas particular relation to the production of hydroxy compounds such asphenols and alcohols. This application is a 5 continuation-impart ofapplication Serial No.

725,077 filed May 11, 1934.

An object of the invention is to provide an improved vapor phase processfor the hydrolysis of organic halides.

A more specific object of the invention is to provide an improved vaporphase process for hydrolyzing monochlorbenzene to phenol.

It has previously been proposed to conduct the vapor phase hydrolysis oimonochlorbenzene to 16 phenol by passing the reaction mixture ofmonochlorbenzene and steam over a porous catalyst such as silica gelwhich may advantageously be impregnated with a metal salt possessed ofcatalytic activity. cuprous chloride is an example 20 of a metal saltwhich has been found to greatly enhance the catalytic activity of silicagel. However, a catalyst formed of silica gel impregnated with cuprouschloride maintains its acitivity for I only a short time before itbegins to deteriorate. 25

the temperature, the purity of the silica gel and the gases, and to someextent. possibly upon the f is possessed of much lower catalyticactivity than silica gel impregated with cuprouschlorldm i It has-beensuggested in Patent No. 1,884,710 issued October 25, 1932 to R. L.Jenkins et al. that 40 the deleterious effects produced, byvolatilization of the cuprous chloride could be avoided by passing thevapor mixture of steam and monochlorbenzene over copper just prior tothe introduction or the vapors to the catalyst. This passage 45 of thereacting mixture over copper is said to result in the formation of avery small amount of cuprous chloride vapor. This amount is so smallthat tests made by applicant show the reacting vapor mixture in theJenkins process is so only about two or three per cent saturated withcuprous chloride vapor.

The present invention is based upon the discovery that superior resultsare obtained by the addition of cuprous chloride vapor to the reaction'66 mixture in such amounts that the mixture is The rate ofdeterioration will depend upon 7 from about ten to eighty per centsaturated with cuprous chloride vapor. Below the lower limit specified,the cuprous chloride vapor is present in insumcient amount to produceoptimum catalytic activity. Above the upper limit specified, 5 there isno gain in activity to compensate for other dificulties that arise inconnection with the use of large amounts of cuprous chloride.

In carrying out the invention in connection with the hydrolysis ofmonochlorbenzene to 10 phenol, cuprous chloride vapor is added to areaction mixture of monochlorbenzene and steam and this is then passedover a silica gel catalyst. The silica gel may have been previouslyimpregnated with cuprous chloride it so desired, but this is notessential to obtain the results of the invention. The ratio of steam tomonochlorbenzene vapor is preferably about 1 to 1. The preferredreaction temperature is about 550 C. p g t The cuprous chloride vaporsmay be supplied by passing the initial mixture of steam andmonochlorbenzene or either over a bath of molten cuprous chloride. Thepercentage saturation of the reaction mixture with cuprous chloride maybe varied by changing the temperature, or the velocity of the vapors andthe extent of the bath.

By a proper adjustment of one or more of these. factors the amount ofcuprous chloride vapor in the reaction mixture is so regulated that itis from ten to eighty per cent of what the mixture would contain it itwere saturated with cuprous chloride vapor at the reaction temperature.Cuprous chloride is a rather volatilesalt and has a vapor pressure at550 C. of about three. or four millimeters of mercury. agas completelysaturated with cuprous chloride vapor, .CuzClz, at this temperature,would-hold about one gram of cuprous chloride per mole of gas.

Another method of introducing, cuprous chloride vapor into the mixtureof steam and mono chlorbenzene in the required amount is to first addhydrochloric acid vapors to the mixture and then pass the same overcopper or through a cop.- per tube to eilect a reaction between the acidand copper, forming cuprous chloride.

Where the cuprous chloride vapors are introduced into the mixture ofsteam and monochlorbenzene by passing the mixture over molten cuprouschloride, there is some possibility that metallic copper may bedeposited upon the silica gel, particularly when the higherconcentrations of, cuprous chloride vapor are used in the reacting gasmixture. This deposition of copper is undesirable because it results ina gradual Consequently, 35 Y 3 inventionwhich consists in addinghydrochloric acid to the reaction mixture in suflicient amount tosuppress the formation of copper. v

The amount of hydrochloric acid necessary to 4 prevent the formation offree metal upon the catalyst-beddepends upon the particular metal saltused in' the process and the nature of the reacting substances, and uponthe temperature at which the reaction is conducted. The amount requiredfor any specific case is readily determined by trial.

The following is a specific example of a run embodying this invention.The reacting mixture contained one mole of steam to one mole ofmonochlorbenzene vapor and 0.425 gram of cuprous chloride per mole ofmixture. The cuprous chloride vapor was added to'the reaction mixture bypassing this over molten cuprous chloride. The reaction temperature was551 C. The amount of cuprous chloride vapor present was such that at thereaction temperature the reaction mixture was about 50% saturated withcuprous chloride vapor. A quantity of hydrochloric acid gas sumcient toprevent the deposition of copper under these conditions will be presentif the steam is formed by the volatilization of a 0.46 normal solutionof hydrochloric acid. This gives a gas mixture which will containsomewhat less than one mole of hydrogen chloride for one hundred molesof water. Since hydrogen chloride is one of the products produced by thereaction between steam and monochlorbenzene vapor, its introduction intothe mixture of reacting gases will theoretically have a tendency torender the conversion of monochlorbenzene to phenol less complete thanif it were absent, but with the v small amounts which are sufllcient tosuppress the formation of metals on the catalyst bed this efl'ect issmall and is far outweighed by the advantages gained through theincreased activity of the catalyst and the increased period of time overwhich the catalyst maintains its activity.

In the example just given the rate of gas flow through the catalystchamber was such as to give a contact time of 0.5 second. Thiscorresponds to a space velocity of 7200 per hour with the gas volumefigured at the reacting temperature; or a space velocity of practically2400 per hour if the gas volume passing through the catalyst chamber isreduced to 0! C. In one pass over the catalyst about 12% of themonochlor- -benzene in the reaction mixture was converted to phenol.

While a temperature of about 550 C. is preferred it is to be understoodthat the invention is not limitedto this temperature and that othersuitable temperatures can be used. The exact temperature to be employedat any given time should be determined by a consideration of all of theeconomic factors of the process at such time, such as the cost ofcatalyst and equipment, percentage recovery, cost of raw materials, andthe like. The space velocity can also be varied over a wide range.

' per cent saturated with cuprous chloride a comparatively small drop inthe catalyst temperature 'will result in the deposition upon it of solidcu-' prous chloride. Possible difllculties due to this monochlorbenzenevapor and steam, said mixture are 'not compensated for by sumcientlyincreased catalytic activity.

The yield of phenol is high. A final conversion of monochlorbenzene tophenol of over of the theoretical can be obtained by recirculating 5 themonochlorbenzene that is not converted in a single pass over thecatalyst.

By carrying out the conversion of monochlorbenzene tophenol according tothe methods of this invention, the catalyst is maintained at-a highstate of activity except, insofar as this is gradually reduced by, thedeposition of carbon.

- The carbon deposit ultimately reduces the-catalytlc activity to suchan extent'that it becomes desirable to suspend operations for asuflicient time to regenerate the catalyst. .This can be done withoutremoving the silica gel from the catalyst chamber. Preferably nitrogenor some other inert gas is first passed through the catalyst chamber ata temperature of about 600 C. to carry off volatile compounds. Air isthen passed through the catalyst at a .temperature which is preferablysomewhat above the reaction temperature to burn off the carbon ortarrymaterial. After this the catalystis ready'for a new 11m.

The practical life of the catalyst between regenerations is preferablymaintained from 5 to 15 hoursby controlling the reaction temperature.

' the purity of thecatalyst and of the monochlorbenzene, the spacevelocity, and the depth of the catalyst bed in accordance with theeconomic factors of the process. The catalyst life between regenerationsmay be increased beyond the above by employing lower temperatures orlower'space velocities with a resultant lower yield per'unit of time.The total life of a single catalyst extends to many regenerationswithout loss of its activity.

In carrying out the invention, after the gases leave the reactionchamber they'are cooled sufflciently to deposit solid cuprous chloridewhich is recovered and returned to the process without substantial loss.The remaining gases are treated in the vapor phase or are condensed andtreated in the liquid phase to separate phenol and theunreactedmonochlorbenzene which latter is recirculated through theprocess. Any suitable method of separation may be used. The hydrochloric acid is recovered from the exit gases and constitutes aby-product of the process.

The invention is claimed as follows:

1. The process of hydrolyzing monochlorben-- zene in the vapor phasewhich comprises passing through a porous silica catalyst bed maintainedat a suitable reaction temperature, a mixture of containing cuprouschloride vapor in excess of an amount obtainable bypassing said mixtureover heated copper. I

,2. The process of hydrolyzing an organic halide in the vapor phasewhich comprises passing through a porous silica catalyst bed maintainedat a suitable reaction temperature-a mixture of thehalide vapor andsteam containing cuprous chloride vapor in excess of 10% of the amountrequired to saturate the mixture at the reaction temperature.

3. The process of hydrolyzing monochlorobe zene in the vapor phase whichcomprises passing through a porous silica catalyst bed maintained at asuitable reaction temperature, a mixture of monochlorobenzene vapor andsteam containing cuprous chloride vapor in excess of 10% of the amountrequired to saturate the mixture at the reaction temperature.

4. The process of hydrolyzing monochloroben- 15 assaeoo zene in thevapor phase to produce phenol, com

prising mixing the vapors of monochlorobenzene and steam and passing thesame over a bath of molten cuprous chloride to produce a vapor mixturethrough a porous silica catalyst bed to eiiect hydrolysis.

5. The process of hydrolyzing monochlorobenzene in the vapor phase toproduce phenol, comprising passing a vapor mixture of monochlorobenzene,steam, and hydrogen chloride over a substance containing copper toproduce a vapor mixture containing cuprous chloride in an amount notless than 10% of saturation at the reaction temperature, and thereafterpassing the reaction mixture through a porous silica catalyst bed atreaction temperature to eflect hydrolysis.

6. The process 01 hydroiyzingmonochlorobenzene in the vapor phase toproduce phenol, comprising mixing the vapors of monochlorobenzene and ofa dilute solution of hydrochloric acid and passing the same over asubstance containing copper to produce a vapor mixture containingcuprous chloride in an amount in excess of 10% of saturation at thereaction temperature, and thereafter passing the reaction mixturethrough a porous silica catalyst bed to eflect hydrolysis. I

v 'I. In the vapor phase hydrolysis of monochlorobenzene on a silica gelcatalyst, the improvement which comprises adding cuprous chloride vaporto the reacting mixture of steam and monochlorobenzene vapor insuflicient quantity to increase the catalytic activity of said silicagel' catalyst, and hydrochloric acid gas in suflicient quantity tosuppress the deposition of metallic copper on the silica gel catalyst.8. The method of carrying out a catalytic reaction which comprisesmixing the vapors of the substances to be combined together with thevapor of a volatile metal salt possessed of catalytic activity and thevapor of an acid which prevents the deposition upon the catalyst ofireemetal from the volatile metal salt, and passing the mixture over aporous catalyst bed.

9. The method of making phenol which comprises mixing the vapors otmonochlorobenzene and water with the vapor 01' a volatile metal saltpossessed of catalytic activity and the vapor ofv an acid which preventsthe deposition upon the catalyst of free metal from the volatile metalsalt, and passing the mixture through a porous catalyst bed.

10. The method of making phenol which comprises mixing the vapors ofmonochlorobenzene and steam with cuprous chloride vapor, passing themixture over a porous silica catalyst bed at reaction temperatures.condensing-the cuprous chloride from the exit gases and returning thecuprous chloride to the process, separating the phenol from the exitgases, and returning the unreacted monochlorobenzene in the exit gasesto the process.

ALBERT W. MEYER.

